That service is for as many years as they receive financial support (for example, a two-year degree is repaid by two years of service, just as the scholarship scheme with MoE operates currently).
Only if they leave the Cook Islands to work overseas would they need to repay the money.
Meitaki maata e kia manuia,
Dr Debi Futter-Puati
The University of the South Pacific
Cook Islands Campus